There has, in the recent past, been considerable activity in the development of what is known in the trade as "child resistant packaging," which permits opening by adults without undue difficulty, as by following printed instructions, and presents substantial obstacles to being opened by children incapable of comprehending and following the necessary instructions. However, such child resistant packaging has, in the past, not been entirely satisfactory as being too difficult or too easy to open, and usually presenting at least some apparent entry structure, which may defeat the intended purposes.